1. Field of the Invention
The present invention relates to an extracting method of a pattern contour, an image processing method, a searching method of a pattern edge, a scanning method of a probe, a manufacturing method of a semiconductor device, a pattern inspection apparatus, and program. The present invention relates to, for example, evaluation of a fine pattern in a manufacturing process of the semiconductor device.
2. Related Background Art
In a manufacturing process of a semiconductor device, an optical microscope or a scanning electron microscope (hereinafter referred to as an SEM) is used to inspect a fine pattern.
In recent years, multifactorial inspection and control of patterns have extensively implemented with a positive use of two-dimensional configuration information of a pattern image outputted from an inspection apparatus. Basis of this technique is a technique of extracting a contour of the pattern from an inspection image thereof given by a gray scale or color distribution.
For a simply linear pattern, for example, as shown in FIG. 43, a method has heretofore frequently been used comprising: searching an edge along directions SD202 vertical to a longitudinal direction of a linear pattern PT200; and analyzing gray scale data at the time to calculate an edge position based on a threshold value method.
In addition, for a pattern having a schematically convex shape, for example, a hole pattern PT210 shown in FIG. 44, there is a method of radially searching a pattern edge as shown by searching directions SD212 in the drawing. This method is described, for example, in Japanese Patent Application Laid-Open Nos. 7-27548 and 2001-91231.
However, even with the use of the above-described method, edges of some patterns are wrongly detected, for example, as patterns shown in FIG. 45, the contour shape of which are complicated, and when the edges are simply searched in directions SD214 extending in parallel with one another. Since an image Img2 in FIG. 45 includes a plurality of patterns PT2, PT4, PT6, the detected edges have to be attributed to any of the patterns, respectively. For this, an operator needs to designate a region where the pattern exists prior to the search of the patterns. Alternatively, the method has to comprise: performing image matching with design data to automatically attribute the edge; or again grouping extracted edge point sequence data. Any arrangement requires complicated processing, inspection efficiency has thus not been satisfactory.
Furthermore, when a plurality of patterns similar to one another exist in the image, it is frequently necessary to automatically and selectively designate a specific pattern from the plurality of patterns and to inspect the pattern. In this case, the method described, for example, in Japanese Patent Application Laid-Open No. 2001-148016 can be used, but it is difficult to apply this method to cases other than a case in which the plurality of patterns are regularly arranged. Since the matching is performed by calculation of correlation among gray scale image data, a long processing time has been required.
There have been proposed a large number of methods of preferably detecting a pattern edge for patterns having complicated contours. In the searching of the pattern edge, it is desirable to set the edge searching direction to a direction substantially orthogonal to the pattern edge in order to enhance solution of the edge position.
However, even when an edge of a polygon PLG2 shown in FIG. 46 is set as a schematic pattern edge for a pattern PT44 shown in the figure, and as long as the edge is searched in a direction along a straight line, the edge is searched in a direction similar to that of the edge as shown by searching directions SD216c, SD216d. In this manner, it is sometimes difficult to search the edges in directions crossing at right angles to all the pattern edges.